Porblem with ode 45 solver

Question

imran 2015-10-30

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/251909-porblem-with-ode-45-solver

评论： Torsten 2015-11-2

hi I am trying to solve nonlinear state space int the form

xdot= Ax+R(x,u)
y= S(x,u)
i have written a function given below
   function xdot = system(t,x,u)
    Tab=sqrt(2/3)*[cos(x(1)) cos(x(1)-2*pi/3) cos(x(1)+2*pi/3)
    -sin(x(1)) -sin(x(1)-2*pi/3) -sin(x(1)+2*pi/3)
    1/sqrt(2) 1/sqrt(2) 1/sqrt(2)]
    wc=2*pi*50;
    L=1.35e-3;
    R=.056;
    C=50e-6;
    Rc=.131;
    Lc=0.96e-3;
    P=10e3;
    Q=5e3;
    KpllI=5000;
    KpPPL=2.1;
    Kid2=460;
    Kpd2=1;
    Kiq2=460;
    Kpq2=1;
    udq= Tab*u;
    A=[0 KpllI 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
    0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
    0 0 -sqrt(2)*wc 0 wc*wc 0 0 0 0 0 0 0 0 0 0 0 0
    0 0 0 -sqrt(2)*wc 0 wc*wc 0 0 0 0 0 0 0 0 0 0 0
    0 0 -1 0 0 0 0 0 1 0 0 0 0 0 -1 0 0
    0 0 0 -1 0 0 0 0 0 1 0 0 0 0 0 -1 0
    0 0 0 0 0 0 0 0 -1 0 0 0 0 0 0 0 0
    0 0 0 0 0 0 0 0 0 -1 0 0 0 0 0 0 0
    0 0 0 0 0 0 0 0 -R/L 0 0 -1/L 0 0 0 0 0
    0 0 0 0 0 0 0 0 0 -R/L 0 0 -1/L 0 0 0 0
    0 0 0 0 0 0 0 0 0 0 -R/L 0 0 -1/L 0 0 0
    0 0 0 0 0 0 0 0 1/C 0 0 0 0 0 -1/C 0 0
    0 0 0 0 0 0 0 0 0 1/C 0 0 0 0 0 -1/C 0
    0 0 0 0 0 0 0 0 0 0 1/C 0 0 0 0 0 -1/C
    0 0 0 0 0 0 0 0 0 0 0 1/Lc 0 0 -Rc/Lc 0 0
    0 0 0 0 0 0 0 0 0 0 0 0 1/Lc 0 0 -Rc/Lc 0 
    0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -Rc/Lc];
    w= KpllI*x(2)+KpPPL*udq(2);
    vld=Kid2*x(7)+Kpd2*(x(3)-x(9))+udq(1)-w*L*x(10);
    vlq=Kiq2*x(8)+Kpq2*(x(4)-x(10))+udq(2)-w*L*x(9);
    ;
R=[KpPPL*udq(2) % u(2)= voq
udq(2)
0
0
(udq(1)*P-udq(2)*Q)/((udq(2).^2)+(udq(1).^2))
(udq(1)*P+udq(2)*Q)/((udq(2).^2)+(udq(1).^2))
0
0
(vld*1/L)+w*x(10)
(vlq*1/L)-w*x(9)
0
w*x(13)
-w*x(12)
0
(-udq(1)*1/Lc)+w*x(16)
(-udq(2)*1/Lc)+w*x(15)
0];
xdot=A*x+R;
and the main file with 
t=0:100e-5:5;
wc=50;
u= [240*sqrt(2)*sin(wc*t+pi/2)
240*sqrt(2)*sin(wc*t-2*pi/3+pi/2)
240*sqrt(2)*sin(wc*t+2*pi/3+pi/2)];
x0=zeros(17,1);
odeOptions = odeset('RelTol',1e-6);
[t,y]      = ode45(@system,t,x0,odeOptions,u);
Tab=sqrt(2/3)*[cos(y(:,1)) cos(y(:,1)-2*pi/3) cos(y(:,1)+2*pi/3)
-sin(y(:,1)) -sin(y(:,1)-2*pi/3) -sin(y(:,1)+2*pi/3)
1/sqrt(2) 1/sqrt(2) 1/sqrt(2)];
udq= Tab*u;
The problem i am facing is that multiplication in the last line of code is giving error while in function file it gives no error but do not save the result. Kindly any body suggest me what i am doing wrong. Thanks